JPH01280280A - Arithmetic unit for automatic correction of ship position - Google Patents

Abstract

PURPOSE:To correct a rough position at a high speed with high accuracy by performing two-dimensional pattern matching processing between a chart image and a radar image at the time of detecting the current position of a ship. CONSTITUTION:A matching circuit 15 performs the pattern matching processing between the chart image in a chart image register 10 and the radar image in a radar image register 11 to find a correcting value for the rough position. At this time, a 1st mutual correlation arithmetic circuit 16 calculates a rough two-dimensional mutual correlation value over a wide range and a 1st maximum value position detecting circuit 21 finds the maximum value. Then a 2nd mutual correlation arithmetic circuit 17 calculates a fine two-dimensional mutual correlation value with respect to almost the rough correcting value, and a 2nd maximum value position detecting circuit 22 finds its maximum value as a fine correcting value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for detecting the current position of a ship, and in particular, for automatically correcting the approximate ship position using a nautical chart image and a radar image. The present invention relates to an arithmetic device for automatic ship position correction.

[Prior Art] When a ship navigates a narrow waterway, it is necessary to continuously detect the position of the own ship with high accuracy in order to prevent ship accidents such as running aground. This type of automatic ship position detection method involves determining the hyperbola of the position by measuring the difference in the reception times of synchronized pulse signals from two or more fixed transmitters (long range). na
A method of positioning by observing the deviation of the received frequency of radio waves emitted from satellites due to the Doppler effect (NNSS: navigation)
Radio wave ship position measurement methods such as 5atellite 5ysten) and estimation methods using gyros and logs are used, but these methods are unsuitable for navigation in narrow channels due to their low accuracy.

In order to solve this problem, a device has been proposed that highly accurately corrects the approximate position (coordinates) of a ship detected by the above-mentioned conventional automatic ship position detection method (for example,
(See Publication No. 584).

In the calculation device for automatically correcting own ship's position, the nautical chart virtual radar creation section inputs the nautical chart image and the approximate coordinates P, performs scanning on this image centering on the seat WAP, and creates a nautical chart virtual of the coastline of a predetermined width. Create a radar image.

The radar virtual radar creation section inputs the radar image and the coordinates P, and creates a radar virtual radar image of the coastline in the same way as the nautical chart virtual radar creation section. A correction value for the coordinate P is obtained by performing pattern matching processing on the two virtual radar images created in this way. That is, the correlation value calculation unit calculates a two-dimensional cross-correlation value between two virtual radar images, and outputs the position where the cross-correlation value is maximum as a correction value. Based on this correction value, the own ship's position is displayed on the video display and automatically and continuously corrected.

[Problems to be Solved by the Invention] However, in the conventional calculation device for automatic ship position correction, the cross-correlation calculation by the correlation value calculation unit was performed with a shift amount of one pixel. If the area to be applied is widened, even fast Fourier transform (FFT)
Even if the speed is increased by using the method, the disadvantage is that the pattern matching process takes a long time. Therefore, in order to shorten the processing time, it is necessary to narrow the area in which the cross-correlation calculation is performed or to increase the shift amount of the cross-correlation calculation (on the two-stroke rigging). However, the former method has the drawback that the correctable range becomes narrow, and the latter method has the disadvantage of worsening the correction accuracy.

Therefore, an object of the present invention is to provide an automatic ship position correction calculation device that can correct the general position of a ship at high speed and with high precision.

[Means for Solving the Problems] The calculation device for automatic ship position correction according to the present invention divides the identification target into two values, a logic "1" level and a logic "0" level, centering on the approximate position of the ship. a storage means for storing a nautical chart image in which pixels are arranged two-dimensionally; and a storage means for storing a nautical chart image in which pixels are arranged in a two-dimensional manner, and a reflection point from an object to be identified by the radar is set to a logic "1" level, and other points are set to a logic "0" level, with the above-mentioned approximate position as the center. a second storage means for storing a radar image in which binary pixels are arranged two-dimensionally, and a two-dimensional pattern matching process between the chart image and the radar image;
In the calculation device for automatically correcting own ship's position, the matching means has a two-dimensional correlation between the chart image and the radar image with a shift amount of at least two pixels. a second value calculating means for calculating the correlation and outputting a cross-correlation value of the second value; and detecting a two-dimensional coordinate component indicating the maximum value of the cross-correlation value of the second value, and detecting the detected two-dimensional coordinates. maximum value position detection means for outputting the component as a coarse correction value of the approximate position; and a two-dimensional detection means for detecting the position of the nautical chart image and the radar image with a shift amount of one pixel only in the vicinity of the coarse correction value. a second calculation means for calculating the cross-correlation of and outputting a second cross-correlation value; and detecting a two-dimensional coordinate component indicating the maximum value of the second cross-correlation value, and a second coordinate component for outputting the coordinate components of as detailed correction values of the approximate position;
A maximum value position detecting means is provided.

[Operation] Chart image is converted to VC (X, Y), radar image is converted to VR (X, Y).
In the present invention, as described in detail below,
By performing two-stage cross-correlation calculation, fine correction values (ΔX', ΔY') for the approximate position of the ship are determined at high speed and with high precision. First, in the first step, the coarse two-dimensional cross-correlation values in a wide range are computed by the first value computing means, and the two-dimensional coordinate component (coarse correction value) indicating the maximum value of the coarse cross-correlation values is determined. Next, in the second step, the second calculation means calculates fine two-dimensional cross-correlation values only in the vicinity of the coarse correction value, and calculates the two-dimensional coordinate component indicating the maximum value of the fine cross-correlation values. Use fine correction values. Next, it will be explained in more detail.

In the first stage, the calculation means for the first value is the nautical chart image ■c (x
, y) and the shift value (DX,
OY) and two-dimensional cross-correlation value CR(OX.

DY), (-DXHAX≦DX≦DXI
The shift range is 4AX, -DYHAX≦DY≦DYHAX), and is calculated using the following formula. However, the increment (shift amount) of the shift value OX must be DDX of at least 2 pixels,
The increment (shift amount) of the shift value DY is set to at least two pixels DDY.

However, × indicates logical product.

This cross-correlation calculation yields a rough cross-correlation function for each DDX and DDY. The maximum value position detecting means for the second value detects the shift value (
OX, DY) are output as coarse correction values (ΔX, ΔY). The accuracy of this coarse correction value (ΔX, ΔY) is (+D
DX, + DDY) tare 6° In the second stage, the second calculation means converts the shift value (OX, DY) into (AX-OD
X+ 1 ≦DX≦AX+DDX-1, AY-DDY+
In the shift range of 1 ≦DY≦AY+DDY-1),
Nautical chart image Vc (X, y) with shift amount for each pixel
and radar image VR (X.

The two-dimensional cross-correlation value CR (DX, DY) of the shift value (OX, DY) of Y) is determined according to equation (1). That is, by this calculation, the coarse correction value (
A fine two-dimensional cross-correlation function for each pixel is obtained in the vicinity of ΔX, ΔY). The second maximum value position detecting means detects a shift value (OX
, DY) as fine correction values (ΔX', ΔY'). The accuracy of these fine correction values (ΔX', ΔY') is ±1, that is, one pixel.

[Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the drawings, and FIG. 1 will be described. Referring to FIG. Binary pixels are arranged two-dimensionally, with the coastline at logic "1" level and the rest at logic "0" level, centered around the approximate position P of the ship detected by a radio navigation device (not shown). A nautical chart image register 10 that stores a nautical chart image VC (X, Y), and a nautical chart image register 10 that stores a nautical chart image VC (X, Y) centered on the approximate position P, a logic "1" level for reflection points from the coastline by a radar (not shown), and a logic "O" level for other locations. It has a radar image register 11 that stores a radar image (IVR (X, Y)) in which 2M pixels as levels are arranged two-dimensionally.

The images stored in these image registers 10 and 11 are
The signal is supplied to the matching circuit 15. Matching circuit 15
is the sea map 1 elephant VC (X, Y) and the radar image VR (X,
As described below, the two-dimensional pattern matching process with Y) is performed at high speed, and the correction value <ΔX'
, ΔY′).

The matching circuit 15 has a cross-correlation calculation circuit 16 for the second value. The cross-correlation calculation circuit 16 for the th value shifts tla
(OX, DY) No. 7 range (-DXHAX≦
DX≦DXHAX, -DYHAX≦DY≦DYHAX)
, the shift increment is (DDX, DDY) (however, DDX and DDY are integers of 2 or more), and the marine drawing f
iVc (X, Y) and the shift value of the radar image VR (X, Y) (1)X, 1)Y)
(OX, DY) is calculated according to the above equation (1).

FIG. 2 shows an example of a coarse one-dimensional cross-correlation value CR(DX) with a wide shift range when the shift increment DDX is 2.

A wide range of coarse two-dimensional cross-correlation values CR(DX) obtained by this second value cross-correlation calculation circuit 16.

DY) is supplied to the maximum value position detection circuit 21 of the th value. The maximum value position detection circuit 21 detects a shift value (
OX, DY) is detected, and the detected value is converted into a rough correction value (Δ
X, ΔY). Here, the coarse correction value (ΔX
, ΔY) is (±DDX, ±DDY).

■ Incredible one-dimensional cross-correlation with a wide shift range 1i! ¥CR(
OX), as shown in FIG. 2, the shift value Ox indicating the maximum value indicated by diagonal lines is set as the coarse correction value ΔX.

This coarse correction value (ΔX, ΔY) is supplied to the second cross-correlation calculation circuit 17.

The second cross-correlation calculation circuit 17 generates a shift value ('OX.

DY) shift range (AX-DDX+1≦DX≦AX
+DDX-1, ΔY-[IDY+1≦OY≦ΔY+ 0
[IY-1), two-dimensional cross-correlation value of chart image VC (X, Y) and radar image VR (X, Y) (7) shift value (OX, DY) with shift increment as (1, 1) CR([
lX.

DY) is calculated according to the above equation (1).

FIG. 3 shows an example of a fine one-dimensional cross-correlation value CR(OX) with a narrow shift range.

The fine two-dimensional cross-correlation value CR (DX,
DY) is supplied to the second maximum value position detection circuit 22. The second maximum value position detection circuit 22 detects the shift value (DX, DY) indicating the maximum value of this two-dimensional cross-correlation 1iicR (DX, DY), and converts the detected value into a fine correction value (ΔX', ΔY').

Here, the accuracy of the fine correction values (ΔX', ΔY') is (
±1, ±1).

Fine one-dimensional cross-correlation value CR(OX
), as shown in FIG. 3, the shift value OX having the maximum value indicated by diagonal lines is set as the target correction value ΔX'.

In this way, the cross-correlation calculation circuit 16 for the second value calculates coarse two-dimensional cross-correlation values CR (OX, DY) over a wide range, and the maximum value position detection circuit 21 for the second value calculates the coarse two-dimensional cross-correlation values CR (OX, DY). A rough correction 1ia (ΔX, ΔY) is obtained without showing the maximum value of the cross-correlation value CR (DX, DY), and then the second
The cross-correlation calculation circuit 17 calculates coarse correction values (ΔX, Δ
Fine two-dimensional cross-correlation value C only for the neighborhood of Y)
R(DX, DY), and the second maximum value position detection circuit 22 calculates this fine two-dimensional cross-correlation value CR(DX, DY).
Fine correction values (ΔX′, Δ
Y'), the approximate position of the ship can be corrected quickly and accurately.

Next, specific examples will be given of the case where the approximate position of the ship is corrected by a two-step cross-correlation calculation as in this embodiment, and the case where the approximate position of the ship is corrected by a one-step cross-correlation calculation as in the conventional case. The number of calculations of equation (1) is compared.

First, the number of calculations of the conventional formula (1) is (2×DXHA
X) x (2x DYHAX) times. Therefore,
For example, if DXHAX=DYHAX=40,
The number of calculations of equation (1) is 6400.

On the other hand, the number of calculations of equation (1) in this example is:
(2x DXHAX/DDX) x (2
x DYMAX/DDY)+(2x DD
X-1) x (2x DDY-1) times.

Therefore, for example, when DXHAX=DYHAX=40 and [1DX-DDY=2, the number of calculations of equation (1) is 1609, which is about four times the processing speed compared to the conventional method. Also, DXHAX= DYHAX= 40 Te,
When DDX=DDY=4, the number of calculations of equation (1) is 449, and the processing speed is about 14 times that of the conventional method.

Note that by using a calculation circuit using FFT as the cross-correlation calculation circuit 16 for the second value, the processing speed can be further increased.

Further, in the above embodiment, the nautical chart image register 10 and the radar image register 11 store the nautical chart image and the radar image, respectively. One elephant and a radar virtual radar image may be stored. Furthermore, in this embodiment, the approximate position of the ship is corrected by a two-stage cross-correlation calculation, but the number of stages of the cross-correlation calculation may be greater than that.

[Effects of the Invention] As explained above, according to the present invention, by performing the cross-correlation calculation in multiple stages, it is possible to obtain a correction value for the approximate position of the ship at high speed and with high accuracy. There is.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a calculation device for automatic ship position correction according to an embodiment of the present invention, and FIG. 2 is a cross-correlation calculation circuit for the value shown in FIG. 1 and a maximum value position detection circuit for the value shown in FIG. FIG. 3 is a diagram showing an example of the output of the second cross-correlation calculation circuit and the second maximum value position detection circuit of FIG. 1. 10...Nautical chart image register, 11...Radar image register, 15...Matching circuit, 16.17...
Cross-correlation calculation circuit, 21.22... Maximum value position detection circuit. Figure 2

Claims (1)

[Claims] 1. The object to be identified is logically “1” centered on the approximate position of the ship.
a first storage means for storing a nautical chart image in which pixels divided by binary values of "level" and logical "0" level are arranged two-dimensionally; a second storage means for storing a radar image in which binary pixels are arranged in two dimensions, with the logic "1" level and other pixels as the logic "0"level; and a two-dimensional storage of the chart image and the radar image. and a matching means for calculating a correction value of the approximate position by performing a pattern matching process, wherein the matching means matches the chart image with a shift amount of at least 2 pixels. a first calculation means for calculating a two-dimensional cross-correlation with the radar image and outputting a first cross-correlation value; and detecting a two-dimensional coordinate component indicating a maximum value of the first cross-correlation value. , a first maximum position detection means for outputting the detected two-dimensional coordinate component as a rough correction value of the approximate position; a second calculation means for calculating a two-dimensional cross-correlation between an image and the radar image and outputting a second cross-correlation value; and a two-dimensional coordinate component indicating a maximum value of the second cross-correlation value. a second maximum value position detection means for detecting the detected two-dimensional coordinate component and outputting the detected two-dimensional coordinate component as a fine correction value of the approximate position; 2. The identification target is set to logic “1”, centering on the approximate location of the ship.
a first storage means for storing a nautical chart image in which pixels divided by binary values of "level" and logical "0" level are arranged two-dimensionally; a second storage means for storing a radar image in which binary pixels are arranged in two dimensions, with the logic "1" level and other pixels as the logic "0"level; and a two-dimensional storage of the chart image and the radar image. and a matching means for calculating a correction value of the approximate position by performing a pattern matching process of calculating a two-dimensional cross-correlation between the nautical chart image and the radar image;
a first calculation means for outputting a first cross-correlation value; detecting a two-dimensional coordinate component indicating a maximum value of the first cross-correlation value; and converting the detected two-dimensional coordinate component to the approximate position. a first maximum value position detecting means for outputting a first maximum value position as a first correction value; A two-dimensional cross-correlation with the radar image is calculated, and the second
a second calculation means for outputting a cross-correlation value of the second cross-correlation value; detecting a two-dimensional coordinate component indicating a maximum value of the second cross-correlation value; 1. A computing device for automatically correcting own ship's position, comprising second maximum value position detecting means that outputs the second maximum value position as a second correction value.